And don't forget that boosted-RA are great but rare in a warmongering strategy (you exclude one VC in your reasoning)
I rarely go full Rationalism in war-monger games, and I'm not even saying nerf RA's. I'm on the stance that Rationalism has been nerfed enough. Sure, the opener is an instant-grab, but so what? Make it 5% and nothing changes. People will still grab it right away and the other policies, such as the 50% RA boost, will result in games with just as much overall science. A minor nerf to the opener does nothing.
Secularism can stay at +2. Like I said, move one of the GS slots. The reduction of 5 science is the equivalent of a +1 secularism on 5 different GP slots (likely 4 culture slots and the 1 remaining uni slot). You still get the same benefit as +1 Secularism along with slower GS generation.
Doing it this way greatly lessens the importance of Education. Just nerfing Secularism to +1 still means you are getting an instant +8 science and 6 points to GS generation from Education. The other way means only +5 science and 3 points to GS generation.
There is a drawback adding science in other trees, since science is core, you'll get cookie-cutter builds every game like Trad into Rationalism + Micro picking science buff policies in other trees every game (and according to other comments commerce buff seems to be really nice atm). Science is too core to be buffed that much.
I strongly disagree. Yes, science is core, but the game isn't going to get away from that. We are on two expansions and after what will be one of the last major patches. Science is core, and that fact is here to stay.
To combat it, you spread out science bonuses to give interesting choices. Dropping points into Commerce
and building gold buildings is an opportunity cost. If you choose to go that path and are rewarded with similar science gains, you won't feel forced to go straight into full Rationalism ASAP. To keep things thematic, you attach the science bonuses to other elements, such as Scholasticism and Patronage, or Mercantilism and Commerce.
Think of it like happiness, another core element in the game. Since happiness bonuses are spread all over, I get variety in many of my games. Sure, there will be an optimal choice, but there will always be an optimal choice. You cannot change that. But there
is variety. I've gone Exploration before, since I had a large number of coastal cities and it allowed me to build the Louvre. I get the similar number of smilies if I were to go straight into Ideology tenets, along with the bonuses from Exploration policies.
Science should work the same way: I should be able to choose to play a game with Commerce and Patronage, end up with a competitive amount of beakers, yet get to play a different game that focuses on gold buildings and CS alliances.